Note: This advice is given by the CAP Executive about non-broadcast advertising. It does not constitute legal advice. It does not bind CAP, CAP advisory panels or the Advertising Standards Authority.


In recent years, publicity about the level of CO2 emissions produced by aviation has increased. A wide variety of figures and statistics estimate the amount of CO2 produced by aviation. Some estimate the proportion of global C02 production that can be attributed to aviation; others provide an estimate of the proportion of individual countries’ CO2 emissions caused by aviation. Claims about the amount of CO2 produced by aviation should be based on widely recognised and accepted figures and methods, for example those used by DEFRA (AirportWatch, 12 March 2008).

CAP recommends marketers to include the source of any data used and ensure that the basis of claims is clear. For example, in an advertisement about the Government’s airport policy the ASA considered that readers would interpret the claim “they tell us that aviation already accounts for 13% of UK CO2 emissions – 20% if you include return flights” to mean that those figures had been published by the Government. Because they had not been the claim was considered misleading (Airportwatch, 19 March 2008). Similarly, the ASA considered that the use of an estimated figure for global C02 production that could be attributed to aviation, in an ad that specifically referred to "UK tourists", could be interpreted by readers as a reference to UK CO2 emissions, not global emissions (Ryanair Ltd, 18 July 2007). Conversely, an ad that used a similarly derived figure but stated its source and made clear that it referred to global emissions was judged not to have breached the Code (easyJet Airline Co Ltd, 13 June 2007).

Advertisers who want to make claims based on future projections should ensure that they are clear, conditional and based on accurate data. One advertiser who claimed that flying “could” be 50% cleaner in ten years made clear that the claim was based on the “next generation of aircraft”. Because it was clear that the claim was the advertiser’s opinion and was based on future emissions reductions, the ASA considered that the claim did not breach the Code (easyJet Airline Co Ltd, 2 July 2008). On the other hand, an unconditional and unqualified claim “In Africa, 185 million people will die of diseases directly attributable to climate change” was considered misleading because it presented as absolute fact a prediction that had been based on a worst case scenario (AirportWatch, 12 March 2008).

In response to increased consumer interest in aviation emissions, some airlines have produced ads that claim their airplanes are more fuel efficient than those of their rivals. Marketers should beware of unintentionally making implied claims and should ensure that they have robust substantiation to back them up. One advertiser twice claimed to have lower emissions than most other airlines. Because the ads implied that the planes in the fleet were more efficient than those in other fleets and did not explain that the reduced emissions were a result of carrying more passengers the ASA upheld the complaint (easyJet Airline Co Ltd, 11 April 2007, and easyJet Airline Co Ltd, 2 July 2008).

Another ad stated “Because our planes are younger, they are more efficient and less damaging to the environment". Whilst the advertiser was able to substantiate that their planes were younger, and that they produced less CO2 per passenger per kilometre, their calculation was based on them having had a higher load factor over a set period and therefore did not substantiate a claim in relation to younger planes being less polluting. Whilst the ASA May accept in principal that younger planes are likely to pollute less than older planes advertisers must still hold relevant evidence to support such claims (easyJet Airline Co Ltd, 2 February 2011). Similarly another advertiser implied that their new fleet was "eco-smart" in comparison with competitors’ planes, but relied on evidence that did not directly support their claim and referred to the difference between their own older model aircraft and their new fleet. The complaint was therefore upheld (Finnair, 6 January 2010).

Other claims, such as a comparison of the amount of CO2 produced per passenger compared with other forms of transport, are likely to be acceptable if they are based on robust evidence. The ASA considered an ad that compared the amount of carbon emitted per kilometre by an average diesel car with the CO2 emissions per passenger per kilometre from the Airbus A380 and concluded that the comparison was accurate, fair and unlikely to mislead (Airbus S.A.S., 31 October 2007).

Airlines must ensure that they make a reasonable assessment of how many passengers are likely to occupy a plane when calculating emissions figures per passenger, for example by using the DEFRA average load factor of 79.7%, or alternatively make clear in a footnote that an alternative load factor has been used. The ASA considered that it was acceptable for airplane manufacturers (not airlines) to base the emissions per passenger on the standard configuration of seats by class on the plane, not the specific configuration used by individual airlines (Boeing United Kingdom, 28 November 2007).

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